Add "nix edit" command

This is a little convenience command that opens the Nix expression of
the specified package. For example,

  nix edit nixpkgs.perlPackages.Moose

opens <nixpkgs/pkgs/top-level/perl-packages.nix> in $EDITOR (at the
right line number for some editors).

This requires the package to have a meta.position attribute.
This commit is contained in:
Eelco Dolstra 2017-05-08 18:39:33 +02:00
parent 7689181e4f
commit 03ae5e6459
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75
src/nix/edit.cc Normal file
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#include "command.hh"
#include "shared.hh"
#include "eval.hh"
#include "attr-path.hh"
#include <unistd.h>
using namespace nix;
struct CmdEdit : InstallablesCommand
{
std::string name() override
{
return "edit";
}
std::string description() override
{
return "open the Nix expression of a Nix package in $EDITOR";
}
Examples examples() override
{
return {
Example{
"To open the Nix expression of the GNU Hello package:",
"nix edit nixpkgs.hello"
},
};
}
void run(ref<Store> store) override
{
auto state = getEvalState();
for (auto & i : installables) {
auto v = i->toValue(*state);
Value * v2;
try {
auto dummyArgs = state->allocBindings(0);
v2 = findAlongAttrPath(*state, "meta.position", *dummyArgs, *v);
} catch (Error &) {
throw Error("package %s has no source location information", i->what());
}
auto pos = state->forceString(*v2);
debug("position is %s", pos);
auto colon = pos.rfind(':');
if (colon == std::string::npos)
throw Error("cannot parse meta.position attribute %s", pos);
std::string filename(pos, 0, colon);
int lineno = std::stoi(std::string(pos, colon + 1));
auto editor = getEnv("EDITOR", "cat");
Strings args{editor};
if (editor.find("emacs") != std::string::npos ||
editor.find("nano") != std::string::npos ||
editor.find("vim") != std::string::npos)
args.push_back(fmt("+%d", lineno));
args.push_back(filename);
execvp(editor.c_str(), stringsToCharPtrs(args).data());
throw SysError("cannot run editor %s", editor);
}
}
};
static RegisterCommand r1(make_ref<CmdEdit>());